Both the theoretical spectre of overpopulation and modern economic exigencies have occasioned concern for limiting the human reproductive process. In recent years, great interest has focused on chemical methods for limiting reproduction, including the use of steroids, anti-steroids, polypeptides, antibodies and proteins, and compounds blocking the release or synthesis of the luteinizing hormone, synonymously referred to as lutropin (LH).
Specifically, various polypeptides are known to have contraceptive properties. For example, U.S. Pat. No. 4,016,259 to Kent, Jr. teaches a tetrapeptide, useful as a contraceptive with the following basic amino acid sequence subject to modifications: Thr-Pro-Arg-Lys. Furthermore, U.S. Pat. Nos. 3,855,199 to Foell et al, 3,886,135 to McKinley et al, 3,886,137 to Yardley, 3,928,307 to Foell et al, 3,937,695 to Sarantakis, 3,940,380 to Garsky and 3,941,763 to Sarantakis all teach polypeptides, either exhibiting anti-ovulating activity in mammals or inhibiting LH (lutropin) release, with the basic amino acid sequence p-Glu-D-Phe-Trp-Ser-Tyr-D-Ala-Leu-Arg-Pro-Gly-NH.sub.2, with substitutions or deletions in the amino acid sequences. Finally, U.S. Pat. No. 3,915,947 to Shields teaches a contraceptive compound L Pyroglu-L-Trp-L-Ser-L-Tyr-D-Ala-L-Leu-L-Arg-L-Pro-NHCH.sub.2 CH.sub.3.
A vigorous search continues for more effective compounds having minimal side effects which can be produced in large quantities at reasonable cost.